basically im looking for a variable resistor with a knob or something similiar if you find a bad resistor you can drop in this adjustable resistor as a temporary. i looked at radio chack they have some that say 15k ohms i was told thats the max resistance but it can be set to anything lower but it also said 500 vdc the guy at radio shack said where ever i use it at it must use 500 vdc or elso the resistor wont work properly??? is that true?? what do yall use as a temporary resistor???